feat(hh): /pw command, RAM-only direnv autostart, robust lets-hack; coven→clergy

- add /pw (alias /password): reveal this room's password locally (never
  broadcast); surfaced in the F1 help overlay and the join hint
- direnv-autostart/: cd-to-launch a single real-user session via direnv;
  password is minted in memory at launch (never written to disk, matching the
  RAM-only model) and scoped to the child process. setup.sh installs direnv,
  hooks bash/zsh, and `direnv allow`s the dir
- lets-hack.sh: boot a FRESH server by default (replacing any live one) with a
  --reuse opt-out; add -h/--help/-help; guard against killing the tmux session
  you're attached to; switch-client into the coven when run inside tmux
- rename coven→clergy across rust/python/scripts; tests/test_coven.py→test_clergy.py
- snapshots in-progress hack-house client work (sandbox, themes, net, ui)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

hh/src/crypto.rs

@@ -28,7 +28,7 @@ A099ED8193E0757767A13DD52312AB4B03310DCD7F48A9DA04FD50E8083969EDB767B0CF60\
 60279004E57AE6AF874E7303CE53299CCC041C7BC308D82A5698F3A8D0C38271AE35F8E9DB\
 FBB694B5C803D89F7AE435DE236D525F54759B65E372FCD68EF20FA7111F9E4AFF73";
 
-/// The SRP identity used by every cmd-chat / coven room (server hardcodes this).
+/// The SRP identity used by every cmd-chat / clergy room (server hardcodes this).
 /// The user's chosen display name is independent of this value.
 pub const SRP_IDENTITY: &[u8] = b"chat";